The invention relates to a faucet for tapping a liquid such as beer from a container, in which the liquid is stored under pressure of a gas, e.g. CO.sub.2, and where the faucet comprises a casing with an outlet duct and a valve plug placed therein, for closing the faucet.
Liquids, as e.g. beer, standing under pressure of CO.sub.2 in a container, are inclined to foam when they are tapped by opening the faucet. This is desirable to a certain but not too large degree. If the foam is too violent, the glasses which are to be filled with beer and a suitable amount of foam will be filled with too much foam and too little beer. This is not good enough for the customers. The balance between beer and foam can, however, in these cases be obtained by stripping off the foam and one or more re-fillings, or simply by letting the foam settle and then fill again. By stripping off the foam some of the beer will be lost and refillings cause extra work and take additional time. In the meantime the consumers have to wait and this fact is far from always being satisfactory.
These inconvenient disadvantages have, for obvious reasons, claimed much attention, and over the years there has been many attempts to solve the problem, but so far in a dissatisfactory way.
This is due to several circumstances. The beer is normally tapped in portions in smaller amounts of, for instance 1/4 or 1/2 liter. In this process the condition of the stream is more or less changing all the time, since the beer from standstill is accelerating upon opening of the faucet, and immediately after decelerating to standstill when the faucet is closed.
Some people are using a long time for tapping the beer, while others are faster. Furthermore, the gas pressure, that is the pressure for driving the liquid out through the faucet, can be subject to substantial changes, e.g. by adjusting the reduction valve, or if the container is supplied with too little driving gas. Furthermore, the temperature of the beer can vary significantly and thereby cause the gas pressure to fluctuate.
The conditions for dispensing the beer are in such way subject to even very large and partly also rapidly continuous changes. It has therefore up till now not been possible to control the foam process with a satisfactory result.